Friction: the effect on the ocular surface

The adverse consequences of friction in biological structures include wear and discomfort. The tribological model of the eye comprises two rubbing surfaces and lubrication provided by the complex composition of the tear film. Eyelid movement corresponds to the hydrodynamic regime of the Stribeck curve. This review considers various components of the tribological system of the visual organ, including the "lid wiper", the structure of the "brushes", the role of the glycocalyx, and tear film components relevant to friction. The study separately analyzes the patterns and mechanisms of friction under dry eye conditions, and presents in detail the effects of contact lenses on the tribological components of the ocular surface. The review identifies a number of conditions and diseases that affect ocular surface wear and microtrauma, and outlines possible directions for the development of tribological analysis in clinical practice and approaches to reducing friction between ocular surfaces.